1. Field of the Invention
The present invention relates to an apparatus and method for safely controlling a control rod of a nuclear reactor for a nuclear power plant.
2. Description of the Related Art
Generally, an apparatus for controlling a control rod of a nuclear reactor may control a position and a speed of the control rod, and the like, using an automated algorithm in order to converge an output of heat or neutrons generated by the nuclear reactor to a power demand desired by a user. The apparatus is disclosed in Korean Patent Application No. 10-2002-0047040, and Japanese Patent Laid-Open Publication No. JP 2004150928.
In a nuclear reactor for a nuclear power plant, an output of the nuclear reactor may be controlled by controlling a speed of the control rod formed by a neutron absorber. However, during the controlling process, software or hardware errors may occur and controlling of the control apparatus may be performed in an inverse order. In addition, despite the control apparatus being operated in a normal state, the control rod or a control rod assembly may be withdrawn instantaneously by an external mechanical force resulting from damage to the nuclear reactor, or a rapid change in a flow speed in the nuclear reactor. When the control rod assembly is withdrawn contrary to an intended control, a neutron absorbing function of the control rod may be partially lost, and the output of the nuclear reactor may increase. Such an increase in the output of the nuclear reactor may result in critical safety problems. Accordingly, accident prevention based on a concept of safety design in nuclear power industries may be needed. In this vein, there is a need for an apparatus for sensing such an accident, and preventing a withdrawal of the control rod mechanically in order to prevent a secondary accident when an accident occurs.